The present invention relates to an improved steel tower for supporting high- and very high-tension lines in electric networks, in particular a novel structure as to the cross-section shape, especially for self-supporting towers with the wires arranged side by side or to form a triangle.
It is known that the steel towers of this type for the power supply at a voltage in the range from 230 KV to 1000 KV are formed as a truss structure with steel trussing members mutually joined by bolts. These structures are conventionally and typically in the form of a pyramid with a square or rectangular cross-section, in order to properly utilize the hot-rolled angle irons, commonly used for the bars or trussing members forming the truss structures, which are formed with side flanges bent at right angles.
It is also known that only exceptionally self-supporting steel towers have been made with their cross-section shaped as an equilateral triangle, thereby again with a pyramidal configuration, the pyramid in this case being traingular and not quadrangular. Of course such structures have been assembled by means of welded junctions or by using special section irons with flanges at 60.degree., whereby the advantages obtained in saving the number of trussing members and as to the foundation works are lower than the considerable outlay due to the utilization of non-standard sections. Therefore this particular configuration has been adopted only for steel towers to be installed in certain positions of the supply network which are subject to lower stresses.